The small intestine has a mucosal lining which assists in the last stage of digestion. When harmful substances enter the small intestine, the body has a response mechanism in place to protect you. This is the excretion of excess mucus (in addition to what's already there). This excess mucus is meant to stop the absorption of the harmful substance whether it's a chemical or pathogen. If this happened 3 times a month, our body would simply digest and eliminate the excess. However, many people consume harmful chemicals/pesticides, etc. 3 times a day, never allowing the body the chance to digest and eliminate the excess. This is why people cleanse. The shape of the plaque happens as the buildup distorts the shape of the small intestine over time. I hope this helps to clear things up.